Some would argue there was enough probable cause to bring him in. When witnesses said they heard the kid screaming before the shots were fired.

Bringing him in does not mean arresting/holding him though. It just means getting his statement....if he walks out they would have to arrest him or let him go.

Witnesses did not say they heard 'the kid' screaming, in the initial report at least it was Zimmerman who was reported to be screaming. Even when they played the audio tape for Travon's father for the 1st time, he did not claim it was Trayvon screaming.